The present invention relates generally to radar systems, and specifically to a noise generator which transforms signals from two sets of noise sources into a composite signal which simulates a clutter echo return signal.
In the manufacturing process of radar systems, it is desirable to divide the radar system up into a set of subsystems, and test each subsystem before constructing the complete radar and testing it on location. This approach gives early visibility into the performance of the radar system, and allows corrections to be made to the design before the radar is completely built.
One such subsystem test includes the testing of the radar's signal processing system using ground echo returns (or clutter) before it is attached to the radar receiver. While numerous simulators have been devised to check the performance of radar equipment, some of them require elaborate set-up procedures and are nearly as complex and expensive as the radar systems that they are used to test.
The task of reducing the size, cost and complexity of radar clutter simulators is alleviated, to some degree, by the following U.S. patents, which are incorporated herein by reference:
U.S. Pat. No. 3,732,568 issued to O'Mary et al on May 8, 1973; PA0 U.S. Pat. No. 3,832,712 issued to Goetz et al on Aug. 27, 1974; and PA0 U.S. Pat. No. 4,056,788 issued to Brown et al on Nov. 1, 1977.
All of the prior art cited above disclose signal simulators for testing radar systems. The disclosure of Brown et al is a digital-to-analog noise generator which includes a plurality of memories in which bandwidths, frequencies, and waveforms are stored. While the use of memories allow signal simulators to be flexible in their use, they also increase the complexity and expense of the signal simulator.
The device of O'Mary et al is a radar signal simulator which simulates radar returns to the signal processing portions of a radar system. While the O'Mary device lacks the flexibility of the apparatus of Brown et al, it has a simplicity of design which reduces its expense as well as the complexity of its use. However, while the O'Mary device outputs a simulated clutter signal with a controlled amplitude, a realistic simulation of clutter should include controlled bandwidth Gaussian noise signals with Rayleigh distribution and radar range decorrelation. The present invention is intended to produce such signals while maintaining less size, cost and complexity of alternate schemes.